Friday, February 19, 2016

Getting Past Doors: Modern Options

Dungeon Fantastic has had a preoccupation with doors lately, and I figured I'd throw out some ways of defeating doors in the TL 6+ world. Most of these apply to generic locked doors that are largely intended to keep the honest person honest- not your high-security fare. Truth be told, almost all of these focus on the lock, not the door.

Bump Keys

bump key is a key that has all of the teeth at the shortest possible length- 0. Most locksmiths or hardware shop folks will look at you really funny if you request one of these. Depending on jurisdiction, Bump Keys could be illegal, probable cause for a search, or an item that can be confiscated by police.

Using a bump key is simple- insert the key one notch out, apply sideways pressure to the key in the direction the lock opens, and bump the key into the lock making sure the motion engages the teeth into the lock. 

Bumping is fast and relatively quiet. Bumping doesn't leave many signs of forced entry, especially done with a light touch. Less careful bumping can leave telltale marks on a lock, although your normal beat cop might not pick up on them- I figure most detectives or locksmiths would.

Bumping is limited largely by needing the correct key base to put into the lock. Countermeasures almost all rely entirely on the quality of the lock involved, and generally involve needing specific extra precautions be taken.

For use of a proper bump key in GURPS I'd give a hefty equipment bonus to lockpicking skill- on the order of +5 to +7. This assumes that the bump key is suitable for the door in question, and that the lock doesn't have any countermeasures against bumping.

Credit Card

My workplace is a shared complex with multiple businesses, many of them with dozens of employees. For the longest time, there was a single men's and a single women's room, and the men's room had one stall.

Lines were frequent. Trips to other buildings nearby to use their facilities were common.

Luckily, an old tenant gave me a tip about the location of a hidden bathroom, behind the mysterious door K.
Door K has a very simple lock, no deadbolt, and the lock doesn't have any covering or shield preventing you from sliding a credit card between the latch and the door frame.

Using a credit card or other shim on a door is about as quiet as bumping a door. Success really depends on having good access to the latch, and an appropriate shim (my friend has used a spatula when I wasn't around to bump key open her room for the second time she locked herself out).

The most common counter measure to this method of cracking a door is a plate that hides the latch from outside interference (See example to the right).

Against doors that are vulnerable to being opened with a Credit Card or Shim, I'd give a bonus of +2 to +4 to Lockpicking skill.


The company that has started to glob up the majority of the vacant rooms in the complex I work at installed keypad locks on all of their doors lately. Sadly for them, Keypads are weaker to social engineering and bad operational security than a physical key.

With time and the inclination, opening an electronic keypad and creating a short is definitely within the realm of possibility- although it will be obvious and time consuming, and higher quality locks won't open with loss of power/a short. Electronics Operation (Security) and/or Electronics Repair (Security) are both really useful here.

Alternatively, getting the key code from someone is far simpler in most cases. All it takes is overhearing one person telling someone else the code during orientation, or seeing the right email.

Some locks with keypads don't actually proof against bumping- they only offer an alternative path to opening the lock without removing the original key mechanism already present. Often times manufacturer documentation can provide master passwords and the like that can circumvent security measures.

The manual listed the default password- which had never been changed,
allowing me to change the sign to whatever I wanted


Want to get into an apartment building? Loiter around the front until someone comes in or out, and slip in while the door is still open. If needed, claim that you forgot your key, that your girlfriend is late, or that you forgot your wallet. Piggybacking is easy, requires no tools, and the only risk is that whoever opened the door for you doesn't get suspicious.

College campuses are by far the best location for piggybacking through locked doors.


Numerous power tools have uses in defeating locks/doors. All of these are loud, with some being EXTREMELY FUCKING LOUD.
  • Many locks are vulnerable to being drilled
  • A circular saw appropriate for cutting metal can cut through latches/hinges. This is slow, extremely loud, and potentially dangerous for the saw operator.
  • Thermal torches can cut through latches, or can be used to make holes in doors
  • Jacks can be used much like rams, except instead of swinging a log you allow pneumatic or hydraulic power do the work for you


Shooting a lock can be a really hit or miss proposition. Most breaching done these days is done with a shotgun loaded with a breaching round. The muzzle of the shotgun is placed between the lock and the latch, pointing downwards at a 45 degree angle to minimize the chance of the round hitting unintended targets, and then the round is fired.

All told, if you're going to use a firearm, go with shotgun slugs or a rifle, and be prepared for the possibility of shrapnel.

This is backed up by the stats given in High Tech for Locks. (HT 203). A standard lock has DR 6 and HP3, plus unliving injury tolerance. A 9mm pistol will take 2-3 shots to break such a lock- rolling max damage each time.

In Closing:

Modern breaking and entering definitely has more subtle options available for bypassing physical security, especially once magic is no longer an option. Most of the very loud options are gratifyingly loud to boot, which can really amuse players.


  1. Good post. And then I went and listened to my favorite podcast, and despite being about athletic performance, it was on topic - check out the picture in the post: